[Studies on biosorption of Au3+ by Bacillus megaterium]

Some characteristics of Au3+ biosorption and bioreduction by Bacillus megaterium D01 biomass were reported. The optimum pH value of Au3+ biosorption by strain D01 was 3.0. The biosorption was a rapid process, reaching 95% of the maximal capacity within the first 5 min of contact. Temperature did not affect the biosorption. The biosorptive efficiency(99.1%) and capacity (302.0 mg Au3+/g dry weight biomass) were achieved under the conditions of pH 3.0 and 30 degrees C, both concentration with an initial Au3+/biomass radio of 305 mg/g dry weight for 30 min of the contact. The D01 biomass could reduce Au3+ in the solution to Au0, Au0 on the cells surface and in the contact solution could be crystallized to different forms gold crystals, Au3+ impregnated on SiO2 and alpha-Fe2O3 could be reduced to Au0 by D01 biomass. The results of electrochemical reaction indicated that the strain D01 exhibited a high selectivity for Au3+.